In recent years, there have been many types of prepaid cards being used and of these many types, those that have various types of patterns and designs have been marketed. Along with the widening use of such prepaid cards, there has been an increasing demand by persons wishing to have cards made with their own individual designs and motifs, and special blank cards are being marketed so that people can make their own designs and motifs on them afterwards.
The general method used in order to have an original motif or pattern on a conventional blank card is to employ direct printing onto the surface of the card.
However, when this method is used, there is a considerable lack of immediacy as well as the fact that the method is not suited to the production of small quantities such as one or two cards, and this means that the cost per card is quite high. Not only this, the printed designs are generally exposed on the surface of the card and so there are problems of them being easily scratched and lacking in resistance to plasticizer.
As a result of considering the problems involved in the conventional method, the inventors considered the photograph-quality images that are now possible due to recent advances in thermal transfer technology using the sublimation transfer method, and concluded that if the sublimation transfer recording method was used to transfer an image drawn beforehand onto a thermal transfer sheet, onto a prepaid card, then it would be possible to manufacture original cards far more inexpensively than by the conventional printing method. However, when a laminating machine is used to press and heat and thereby laminate a thermal transfer sheet and a card so that the image is transferred, the lamination performed by a conventional laminating machine involves temperature and pressure conditions (such as a heating temperature of between 100.degree. C. and 130.degree. C. and a pressure of 0.5 to 3.0 kg/cm.sup.2) made it difficult to achieve a transferred image which was clear and without cracking. Moreover, although it is possible to lower the heating temperature to 160.degree. C. (as has been proposed on PCT/JP 87/00228, P66), it is not possible to achieve a precise image by only the adjustment of the transfer temperature.